Inductive devices, such as transformers and inductors provided by coils are often included in small scale, medium scale, or very large scale integration (VLSI) circuits. Typically, inductive devices integrated in these circuits use large coil diameters to obtain a good quality factor (i.e., Q-factor). A good Q-factor is especially important for radio frequency (RF) technology applications. Large diameter coils, however, typically use a large percentage of the available substrate area of an integrated circuit and therefore increase production costs.
Concentric coils are typically located in parallel to a substrate surface. The coils are fabricated in back end of line (BEOL) processing during a metallization process using suitable metallization material. Typically, the coils may consume 50% or more of the total chip area. In addition, the inductivities achieved from the coils are usually not suitable for applications in which the coils will be used not only for signal transmission but also for power transmission.
For these and other reasons, there is a need for the present invention.